Rounding the elements

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Timmy Nguyen Dis 1I
Posts: 107
Joined: Sat Aug 17, 2019 12:17 am

Rounding the elements

Does anyone know how much we're supposed to round when we're using elements from the table? For example, are we supposed to use 1 or 1.008 for Hydrogen, 16 or 15.999 for Oxygen, etc.

Shannon Asay 1C
Posts: 102
Joined: Fri Aug 09, 2019 12:16 am

Re: Rounding the elements

I personally use 1.01 for hydrogen and 16 for oxygen, but I think it's fine to use whatever number is on the periodic table.

Trinity Vu 1D
Posts: 53
Joined: Fri Aug 30, 2019 12:15 am

Re: Rounding the elements

You should always use as many digits as possible, so 1.008 g H for example, when doing calculations and save rounding for sig figs for when you have your final answer because if you round/use signings prematurely while you're still doing calculations it can affect your final answer. It wouldn't affect the final answer by too large of an extent. However, it could mean the difference between getting the question right or getting partial credit instead since it wouldn't be the exact answer the problem is looking for.

Marni Kahn 1A
Posts: 107
Joined: Thu Jul 25, 2019 12:17 am
Been upvoted: 1 time

Re: Rounding the elements

I prefer rounding to the third decimal place max when dealing with any element from the periodic table. That way, your answer is still very precise and you can also round to the nearest significant figure. Although it is tedious to use 1.008 during calculations, it often provides you with a well-calculated answer.

Megan Vu 1J
Posts: 101
Joined: Thu Jul 25, 2019 12:15 am

Re: Rounding the elements

For me, I use Lavelle's IUPAC Periodic Table of the Elements that contains very specific constants. For example, Sodium (Na) has 22.98976928 g. Then, at the end, I round off depending on the smallest amount of significant figures.

SarahSteffen_LEC4
Posts: 67
Joined: Sat Aug 24, 2019 12:17 am

Re: Rounding the elements

Yeah, I personally try to use all of the digits given to me on the periodic table for an element/elements (specifically Lavelle's periodic table), and then I use as many steps as needed to solve the equation, without rounding whatsoever, until the very end, in which I will then round my answer as needed.

Alexa Hernandez 3k
Posts: 74
Joined: Sat Sep 14, 2019 12:16 am
Been upvoted: 1 time

Re: Rounding the elements

When it comes to numbers directly from the periodic table y would recommend not rounding. Use the exact number.

Cynthia Rodas 4H
Posts: 51
Joined: Wed Sep 18, 2019 12:21 am

Re: Rounding the elements

I would recommend using the exact values provided by the periodic table and then use the significant figure rules at the end of the calculation to round off properly.

Prasanna Padmanabham 4I
Posts: 111
Joined: Thu Jul 25, 2019 12:17 am

Re: Rounding the elements

I tend to round to the nearest whole number when I'm trying to come up with like a guesstimate or if I'm doing like a multiple-choice test. For homework or free-response questions on tests, I tend to use the number on the periodic table of elements (so 1.008 for H and 15.99 for O). I round/do sig fig stuff at the very end.

Megan Ngai- 3B
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

Re: Rounding the elements

I typically use the exact numbers that are given on the periodic table. This can prevent your answer from being a little off.

Joanne Lee 1J
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

Re: Rounding the elements

I personally round it to the hundredth place of the decimal place and it usually gets me the same answer as the answer in the solutions manual so that should work but I guess the safest option would be using all the values in the periodic table.

Abhi Vempati 2H
Posts: 104
Joined: Fri Aug 09, 2019 12:17 am

Re: Rounding the elements

I round to the hundredths place, but using Lavelle's IUPAC periodic table definitely helps with fixing inconsistencies when checking answers in the solution manual. I also think that because we all get the same periodic table during exams, we don't have to worry too much about these inconsistencies hurting us.

AngieGarcia_4F
Posts: 120
Joined: Thu Jul 25, 2019 12:17 am

Re: Rounding the elements

I think if we are given a number in the problem we should use that number, but if not then I think it'd be best to just use the number provided on the periodic table provided.

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